Do we need a separate letter for the reservation or is it ok to all be on it?

I am coming to china with some friends (15 of us). We have booked our round trip and also have a hotel reservation.

We were going to apply for visas individually through a third party. Do we need a separate letter for the reservation or is it ok to all be on it?

How can I go about booking an appointment at the Chinese embassy in san francisco?